You can expand your home up to 5 times:
Initial house: 17,400 Bells,Living Room expansion: 148,000 Bells, Basement: 49,800 Bells,
2nd house upgrade: 398,000 Bells
2nd floor: 798,000 Bells,Total cost: 1,410,800 Bells. YOU CAN DO THIS IN 4 to 5 days if
you use the following cheat code to get bells (30,000 bells.) To get the bells, do the
following. Go to Tom Nook's store. Pick "Other Things" He'll say, "This is all I have to
offer" Pick "Say Code" Then, ENTER THIS CODE. WB28pARAcnownUjMCK%hTk8JHyrT & press the
start button. Tom will say "I see, I see" 30,000 bells have arrived for you from some
weird name. Open the present. It will be 30,000 bells. Do this 3 times. Then, you'll have
90,000 bells. Go the the Post Office and chose "deposit" and pay off your 1st 17,400
bells. Then go to Tom Nooks and he'll ask you if you want to upgrade. Answer Yes PLEEESE.
Your house will be upgraded the next day. Then, on this day, go to Tom Nooks and enter the
30,000 Bell code again. Do it 3 times so you'll have 90,000 bells. Go to the post office
and pay off as much as you can. Save your game & quit. Then, after you've saved, start
your game again. You can THEN enter the code 3 MORE times in a row! And, get 90,000 more
bells. If you don't have enough money to pay off your mortgage, pay what you can at the
Post office and save and quit the game. Then start the game again. You can use the code to
get (THREE 30,000 bells) 10 times each day (3 times per playing period.) But, you must
save & quit after entering the code 3 times or Tom Nook will say he's out of codes. If you
save and quit, then start the game again, you can enter the code 3 more times (for 90,000)
bells (3 x 30,000.) Unfortunately, you must wait until the next day for each house upgrade
to be completed. So, it takes 4 or 5 days total. Don't forget to go to the Post Office to
pay down your mortgage. And when each mortgage upgrade is paid in full (You'll know, your
character will say "Yea, I', debt free!!",) DON'T FORGET to go to Tom Nooks! He'll ask if
you want to upgrade again. Keep doing this each day until you have the final upgrade.
After you get the 2nd floor (the last upgrade,) you can pay it off a little at a time. You
don't have to pay it all off at once. You can use the 30,000 bell code even after your
house is upgraded. Good luck.